KULINICH, E. V. On topologically equivalent Morse functions on surfaces. Methods of Functional Analysis and Topology, [S. l.], v. 4, n. 1, p. 59–64, 1998. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/54. Acesso em: 4 feb. 2026.